A. Meat quality

The energy required for muscle activity in the live animal is
obtained from sugars (glycogen) in the muscle. In the healthy and well-rested
animal, the glycogen content of the muscle is high. After the animal has been
slaughtered, the glycogen in the muscle is converted into lactic acid, and the
muscle and carcass becomes firm (rigor mortis). This lactic acid is necessary to
produce meat, which is tasteful and tender, of good keeping quality and good
colour. If the animal is stressed before and during slaughter, the glycogen is
used up, and the lactic acid level that develops in the meat after slaughter is
reduced. This will have serious adverse effects on meat quality.

Pale Soft Exudative (PSE) meat (Fig.
1)

PSE in pigs is caused by severe, short-term stress just prior
to slaughter, for example during off-loading, handling, holding in pens and
stunning. Here the animal is subjected to severe anxiety and fright caused by
manhandling, fighting in the pens and bad stunning techniques. All this may
result in biochemical processes in the muscle in particular in rapid breakdown
of muscle glycogen and the meat becoming very pale with pronounced acidity (pH
values of 5.4-5.6 immediately after slaughter) and poor flavour. This type of
meat is difficult to use or cannot be used at all by butchers or meat processors
and is wasted in extreme cases. Allowing pigs to rest for one hour prior to
slaughter and quiet handling will considerably reduce the risk of PSE.

Dark Firm and Dry (DFD) meat (Fig.
1)

This condition can be found in carcasses of cattle or sheep
and sometimes pigs and turkeys soon after slaughter. The carcass meat is darker
and drier than normal and has a much firmer texture. The muscle glycogen has
been used up during the period of handling, transport and pre-slaughter and as a
result, after slaughter, there is little lactic acid production, which results
in DFD meat. This meat is of inferior quality as the less pronounced taste and
the dark colour is less acceptable to the consumer and has a shorter shelf life
due to the abnormally high pH-value of the meat (6.4-6.8). DFD meat means that
the carcass was from an animal that was stressed, injured or diseased before
being slaughtered.

Spoilage of meat

It is necessary for animals to be stress and injury free
during operations prior to slaughter, so as not to unnecessarily deplete muscle
glycogen reserves. It is also important for animals to be well rested during the
24-hour period before slaughter. This is in order to allow for muscle glycogen
to be replaced by the body as much as possible (the exception being pigs, which
should travel and be slaughtered as stress free as possible but not rested for a
prolonged period prior to slaughter). It is important that the glycogen levels
in the muscles of the slaughtered carcass are as high as possible, to develop
the maximum level of lactic acid in the meat. This acid gives meat an ideal pH
level, measured after 24 hours after slaughter, of 6.2 or lower. The 24h (or
ultimate) pH higher than 6.2 indicates that the animal was stressed, injured or
diseased prior to slaughter.

Lactic acid in the muscle has the effect of retarding the
growth of bacteria that have contaminated the carcass during slaughter and
dressing. These bacteria cause spoilage of the meat during storage, particularly
in warmer environments, and the meat develops off-smells, colour changes,
rancidity and slime. This is spoilage, and these processes decrease the shelf
life of meat, thus causing wastage of valuable food. If the contaminating
bacteria are those of the food poisoning type, the consumers of the meat become
sick, resulting in costly treatment and loss of manpower hours to the national
economies. Thus, meat from animals, which have suffered from stress or injuries
during handling, transport and slaughter, is likely to have a shorter shelf life
due to spoilage. This is perhaps the biggest cause for meat wastage during the
production processes.

Bruising and injury (Fig. 2 and Fig.
3)

Bruising is the escape of blood from damaged blood vessels
into the surrounding muscle tissue. This is caused by a physical blow by a stick
or stone, animal horn, metal projection or animal fall and can happen anytime
during handling, transport, penning or stunning. Bruises can vary in size from
mild (approx. 10-cm diameter) and superficial, to large and severe involving
whole limbs, carcass portions or even whole carcasses. Meat that is bruised is
wasted as it is not suitable for use as food because:

· It is not
acceptable to the consumer;

· It cannot be used for
processing or manufacture;

· It decomposes and spoils
rapidly, as the bloody meat is an ideal medium for growth of contaminating
bacteria;

Bruising is a common cause of meat wastage and can be
significantly reduced by following the recommended correct techniques of
handling, transport and slaughter.

Injuries (Fig. 4) such as torn and haemorrhagic muscles and
broken bones, caused during handling, transport and penning, considerably reduce
the carcass value because the injured parts or in extreme cases the whole
carcass cannot be used for food and are condemned. If secondary bacterial
infection occurs in those wounds, this causes abscess formation and septicaemia
and the entire carcass may have to be condemned.

B. Hides and skins
quality

Hides and skins should have the highest value of any product
of slaughter animals, other than the carcass. This is particularly so of cattle
hides and small ruminants and ostrich skins. In the case of pigs and poultry,
the skin forms part of the edible meat.

Useful leather can be made only from undamaged and properly
treated skins. Proper handling of these items is important to produce a valuable
commodity. Careless damage to hides and skins will cost the industry much
loss.

Hides and skins of slaughter livestock (Fig. 5) can be damaged
by thoughtless handling and treatment of these animals in the following
ways: